DMS-20LCD-4/20 Series

Transcription

1 Series 4-20mA Input Loop-Powered Ultra-Low 1.8V Loop Drop, 3½ Digit LCD Display Process Monitors FEATURES Super-low loop drop: 1.8V typical, 2.0V max. Self-powered, no separate supply required Unipolar, Bipolar, and Positive Reading Models Subminiature package Less than 0.90 behind-thepanel depth Large, 0.37"/9.4mm high, sunlight-viewable LCD display Non-interacting gain (span) and offset (zero) 20-turn potentiometers DIP-switch selectable range and decimal points Hundreds of different input/readout combinations Vibration-resistant package; reliable screw-terminal input connections Order Online from The DMS-20LCD-4/20 Series produces the lowest loop voltage-drop of any comparably priced, 4-20mA input, 3½ digit LCD-display process monitors: 1.8V typical, 2.0V max. This super-low drop means its nominal loop resistance (burden) is less than 100 Ohms! All operating power is derived solely from the 4-20mA loop current no separate power source is required! The simple 2-wire hookup allows the DMS-20LCD-4/20 Series to be connected anywhere in the loop All decimal-point and range-change selections are made via a six-position DIP switch featuring vibration-resistant, gold-plated contacts there are no jumpers or solder gaps to ever open or close. Both gain (span) and offset (zero) adjustments are performed with precision, 20-turn potentiometers. Three different models are available for unipolar, bipolar, and positive display reading applications. The DMS-20LCD-4/20 s DIP switch and adjustment potentiometers can accommodate literally hundreds of different input-current/ output-reading combinations. And, connections to the current loop are made via a reliable, two-position, screw-type terminal block. The DMS-20LCD-4/20 Series subminiature package houses a large, 0.37"/9.4mm high digits, LCD display that can be read in virtually all lighting conditions including direct sunlight. An optional bezel assembly, featuring screw fasteners and a rubber seal, simplifies panel mounting and provides excellent resistance to environmental dust and moisture. All these outstanding features combine to make the DMS-20LCD-4/20 Series the perfect meters for OEM 4-20mA current-loop process monitoring instrumentation. 3½ DIGIT A/D CVERTER DATA DP1 DP2 DP3 ZERO ADJUST GAIN ADJUST BAND-GAP REFERENCE CIRCUIT DIP SWITCHES 5V 5V DC/DC CVERTER CURRENT TO VOLTAGE CVERTER Figure 1. DMS-20LCD-4/20 Series Simplified Schematic TB1 1 2 LOOP INPUT Order Online: MPM_DMS20LCD-4/20_B00 Page 1 of 5

2 Performance/Functional Specifications Typical at TA = 25 C, unless otherwise noted. Current Loop Inputs Min. Typ. Max. Units Full Scale Input Range ➀ ma Input Impedence ➁ Ω Voltage Drop ➁ Volts Overvoltage Protection ➀ ±40 ma Performance Sampling Rate 2.5 reading per second Accuracy (1 minute warm-up): ±0.05%FS ±1 Count Temperature Drift (0 = 60 C) ±0.15 ±0.3 Cnts/ C Display Display Type and Size 3½ digit, 0 37"/9.4mm high LCD Polarity Indication "" for negative readings Overrange Indication "1 _" for negative inputs "1 _" for positive inputs Physical/Environmental Operating Temperature 0 60 C Storage Temperature C Humidity (non-condensing) 0 95 % Case Material Polycarbonate Weight 0.6 ounces (17 grams) ➀ The DMS-20LCD-4/20, using any of the DIP-switch settings described above, can withstand overcurrents, including those resulting from accidental reversepolarity connections, up to ±40mA without sustaining any damage. ➁ Because DATEL's DMS-4/20 loop-powered meters employ active circuitry to convert the loop current into a voltage, the meters' effective series impedance varies in a manner that maintains the loop voltage drop constant over the full 4-to-20mA current range. Listed impedance specification applies at 20mA. Ordering Information DMS-20LCD-4/20S-C Unipolar reading, loop-powered LCD meter DMS-20LCD-4/20B-C Bipolar reading, loop-powered LCD meter DMS-20LCD-4/20P-C Positive reading, loop-powered LCD meter DMS-BZL3-C Bezel assembly DMS-BZL4-C Bezel assembly with sealing gasket DMS-20-CP Panel cutout punch A panel-mount retaining clip is supplied with each model. OPERATING AND SETUP INSTRUCTIS DMS-20LCD-4/20S (Unipolar Reading Model) As shipped, the DMS-20LCD-4/20S is factory calibrated to read "000" for a 4mA input and "1000" for a 20mA input. The following worst-case procedure assumes the DMS-20LCD-4/20S is completely mis-adjusted, i.e., both potentiometers and the DIP switches are randomly set. When performing DIP-switch settings, be sure the DIP switch's small actuators are firmly engaged in their fully- or fully-off positions. 1. Set (full scale span/gain adjust) and (zero/offset adjust) fully clockwise, roughly 22 turns, and place SW1-SW6 to OFF. 2. Select DIP switch setting #2. 1. Set (full scale span/gain adjust) and (zero/offset adjust) fully clockwise, roughly 22 turns, and place SW1-SW6 to OFF. 2. Select DIP switch setting #2. 3. Apply a precision 4mA input, with proper polarity, and adjust until the meter's display reads "000". 4. Apply a precision 20mA input and adjust until the meter's display reads "1000". Repeat steps 3 and 4 to make sure the adjustments do not affect one another. 5. Select the appropriate decimal point by setting SW4, SW5 or SW6 to (DP1, DP2 or DP3 respectively). NOTE: If a display reading other than "000" to "1000" is desired, refer to DIPSwitch Settings Table 1 for SW1SW3 settings. Examples (DMS-20LCD-4/20S-Unipolar Model) 4mA ="0.00" 20mA = "6.00" Use DIP-switch setting #3 in Table 1 and enable decimal point DP2 via SW5. Apply 4mA and adjust so the display reads "0.00". Apply 20mA and adjust so the display reads "6.00". 4mA = "000" 20mA = "800" Use DIP-switch setting #2 in Table 1. Apply 4mA and adjust so the display reads "000". Apply 20mA and adjust so the display reads "800". For these display readings, no decimal points are used. Set SW4, SW5 and SW6 to OFF. 3. Desired display readings are: 4mA = ".000" 12mA = ".250" This example is not as straightforward as the previous two. Notice that 12mA is exactly halfway between 4mA and 20mA. If we assume that the input could go up to 20mA, the display reading would then be: 2 x.250 or ".500". From Table 1 we can now select DIP-switch setting #4 and enable DP1 via SW4. Apply 4mA and adjust so the display reads ".000". Apply 12mA and adjust so the display reads ".250". MPM_DMS20LCD-4/20_B00 Page 2 of 5

3 Table 1. DMS-20LCD-4/20S (Unipolar Model) DIP-Switch Settings ➂ 4mA 20mA to Off Off Off to On Off Off to Off On Off to Off Off On to On On On ➂ When looking up DIP-switch settings in the Tables and the desired display readings can be achieved with either of two different settings, using the higher setting # will produce less sensitive offset () and span () adjustments. Please keep in mind that the DMS-20LCD standard meter (from which the DMS- 20LCD-4/20 is derived) has an accuracy specification of ±2 counts (max.). Thus, it may not always be possible to obtain the exact desired display reading. DMS20LCD4/20B (Bipolar Reading Model) The DMS-20LCD-4/20B's zero-offset circuit differs from the unipolar 'S' model described above in that with the 'B' model, a half-scale 12mA input is normally set to display "000". Therefore, all of the of the DIP-switch settings in Table 2 assume a reading of "000" is desired with a 12mA input. Display readings other than those shown in Table 2 are possible, contact DATEL for more information. When configuring the DMS-20LCD-4/20B for the first time, or when selecting a new range, set both and fully clockwise (roughly 22 turns) to their minimum offset/minimum-span positions, respectively. Then select the desired readings from Table 2 and configure DIP-switches SW1, SW2, and SW3 accordingly. The procedure below illustrates how to calibrate the DMS-20LCD-4/20B to its factory-calibrated readings of "1000" with a 4mA input and "1000" with a 20mA input. When performing DIP-switch settings, be sure the DIPswitch's small actuators are firmly engaged in their fully- or fully-off positions. 1. Set both and fully clockwise. 2. Select DIP-switch setting #1 from Table Apply a precision 12mA input and adjust until the meter's display reads "000". 4. Apply a precision 20mA input and adjust until the meter's display reads "1000". 5. Apply a precision 4mA input and the display should read "1000". Repeat steps 3 and 4 to make sure the two adjustments did not affect one another. Examples (DMS-20LCD-4/20B-Bipolar Model) 4mA = "1.00" 20mA = "1.00" Use DIP-switch setting #5 in Table 2 and enable decimal point DP2 via SW5. Apply 12mA and adjust so the display reads "0.00". Apply 20mA and adjust so the display reads "1.00". Apply 4mA and verify that the display reads "1.00", readjust and if necessary. 4mA = "450" 20mA = "450" Use DIP-switch setting #2 in Table 2. Apply 12mA and adjust so the display reads "000". Apply 20mA and adjust so the display reads "450". Apply 4mA and verify that the display reads "450". Repeat adjustment procedure if necessary. For these display read ings, no decimal points are used. Set SW4, SW5 and SW6 to OFF. 3. Desired display readings are: 4mA = "650" 20mA = "650" Notice that these readings can be obtained using either DIP-switch setting #1 or DIP-switch setting #2 in Table 2. In situations like this where DIP-switch settings overlap, less-sensitive / adjustments can be achieved if the higher DIP-setting # is selected (setting #2 in this example). Apply 12mA and adjust so the display reads "000". Apply 20mA and adjust so the display reads "650". Apply 4mA and verify that the display reads "650". Repeat adjustment procedure if necessary. Table 2. DMS-20LCD-4/20B (Bipolar Model) DIP-Switch Settings ➂ 4mA 12mA 20mA to to 1000 Off Off Off to to 650 On Off Off to to 400 Off On Off to to 250 Off Off On to to 150 On On On DMS-20LCD-4/20P (Positive Reading Model) The DMS-20LCD-4/20P s Zero-Offset circuit is optimized to produce positive readings at both 4mA and 20mA input levels. As shown in Table 3 s first three columns, a 4mA input can be typically adjusted (using, Zero/Offset Adjust) to display any positive reading between 000 and 800. The corresponding 20mA-input reading is then added to the 4mA offset as a differential whose magnitude is varied by adjusting (Gain/Span Adjust). The Differential Range column in Table 3 lists the nominal differential display-readings which can be obtained with at, or very close to, its full-clockwise, minimum span position. The Differential Range column can be used as a guide when configuring the meter for the majority of user applications. Higher differential ranges are obtainable; however, the use of higher differential readings results in correspondingly-lower positive readings with 4mA inputs, that is, s clockwise adjustment-range is reduced. Example #3 below illustrates this concept. Please contact DATEL if there is any doubt as to whether or not the DMS-20LCD-4/20P can be configured for your display readings requirements. The first step when configuring the DMS-20LCD-4/20P for the first time, or when selecting a new range, is to set fully counterclockwise and fully clockwise (roughly 22 turns) to their minimum offset/minimum span positions, respectively. The next step is to calculate the required display differential-reading; this is accomplished by subtracting the desired 4mA display reading from MPM_DMS20LCD-4/20_B00 Page 3 of 5

4 the desired 20mA display reading, disregarding decimal points. Then, using the calculated differential display-reading to select the appropriate DIP-switch setting # from Table 3, configure DIP-switches SW1, SW2, and SW3 accordingly. Make certain that the DIP-switch s small actuators are firmly engaged in their fully- or fully-off positions. The procedure below describes how to calibrate the meter for an application which the DMS-20LCD-4/20P easily accommodates: displaying the output of a 4-20mA transmitter, that is, "04.0" with a 4mA input and "20.0" with a 20mA input. 1. Set fully counterclockwise (minimum offset position) and fully clockwise (minimum differential span position), roughly 22 turns. 2. Subtract 040 from 200 to yield a differential value of 160; use this value to select DIP-switch setting #5 in Table 3. Enable decimal point DP3 by placing SW6 to the position. 3. Set the transmitter s output to 4.0mA and carefully adjust clockwise until the meter s display reads Set the transmitter s output to 20.0mA and adjust counterclockwise until the meter s display reads Set the transmitter back to 4.0mA and slowly adjust clockwise until the display reads Reapply 20.0mA and the display should now read Repeat steps 3, 4 and 5 to make sure the adjustments did not affect one another. Examples (DMS-20LCD-4/20P-Positive Model) 4mA = mA = 950 Use DIP-switch setting #4 in Table 3 since subtracting 650 from 950 yields a differential value of 300. Apply 4mA and adjust until the display reads 000. Apply 20mA and adjust until the display reads 300 (the differential value previously calculated). Apply 4mA and adjust until the display reads 650. Apply 20mA and verify that the display reads mA = mA = This example illustrates the DMS-20LCD-4/20P s capability to display higher differential readings than those indicated in Table 3. This example also illustrates how the DMS-20LCD-4/20P can be used to display the output levels of a 4-20mA loop transmitter with higher precision (0.01mA versus 0.1mA) than described above. Subtracting 400 from 1999 yields a differential of 1599, a value not listed in Table 3. However, use DIP-switch setting #1 in Table 3 since this setting has the highest overall offset/span adjustment capabilities. Enable DP2 via SW5 then apply 4mA and adjust so the display reads Apply 20mA and adjust so the display reads Apply 4mA and adjust until the display reads Apply 20mA and check to see that the display reads or just overranges ( 1 ). Repeat adjustment procedure if necessary. Table 3. DMS-20LCD-4/20P (Pos. Reading) DIP-Switch Settings ➂ Differential Range 4mA Input 20mA Input Off Off Off On Off Off Off On Off Off Off On On On On Table 4. Decimal Point Settings SW4 SW5 SW6 DP1 DP2 DP3 PROGRAMMABLE LOGIC CTROLLER ➀ TRANSMITTER & SIGNAL CDITIER DMS-20LCD-4/20 GAIN (TB1-1) TRANSDUCER INPUT 4-20mA Vsig A/D 4-20mA (TB1-2) ZERO 24V 24Vdc SUPPLY ➀ Shown for illustrative purposes only, may not be present in all applications Figure 2. Typical DMS-20LCD-4/20 Connection Diagram MPM_DMS20LCD-4/20_B00 Page 4 of 5

5 MECHANICAL SPECIFICATIS MECHANICAL DIMENSIS: Inches (mm) TOLERANCES: 2 PL DEC ±0.02 (±0.51) 3 PL DEC ±0.010 (±0.254) WIRE SIZE: 18 to 26 AWG (Solid or stranded) STRIPPING LENGTH: 0.20" (5.08mm) MADE IN USA DMS-20LCD-4/ (1.02) 0.90 (22.9) #2-56 INSERT (3.96) DEEP FRT VIEW (4.75) BEZEL INSTALLATI (32.51) PANEL Zero/Offset Adjust Gain/Span Adjust Back View DIP Switches Loop Input DP1 (SW4) 1.30 (33.0) 1.38 (35.1) Front View DP2 (SW5) DP3 (SW6) 0.80 (20.3) 0.88 (22.4) BEZEL INSTALLATI AND RECOMMENDED DRILL AND PANEL CUTOUT (46.38) RECOMMENDED DRILL AND PANEL CUTOUT DIMENSIS INTERNAL CORNER RADII: (0.81) MAX. BEZEL RETAINING CLIP INSTALLATI 1.07 (27.18) (21.29) (33.93) (41.30) (2.362) DIAMETER (4 REQUIRED) LY WHEN USING OPTIAL BEZEL ASSEMBLY (3.68) (2.95) PANEL MeterCenter W. Peninsula Circle, Chandler, AZ Tel: (480) Toll Free: (800) sales@datelmeters.com Websites: -